Self-mixing interference effects in the LD pumped green laser under the threshold current are observed. The behaviors of laser under the threshold current are more like LED. Based on this, we put forward for the first time the idea that replacing the light source with LED. If so, the lifetime and price of this kind of interferometer, and also the cubage of the interferometer is reduced. The ... [Show full abstract] accurate threshold current of lasers can also be measured using this equipment. This will be great contribution to self-mixing interference effects and its applications.